Underfeed stoker



July 5, 1938. E. B. BIRKENBEUEL UNDERFEED STOKER Filed April 11, 1936 Patented July 5, 1938 UNITED STATES PATENT OFFICE UNDERFEED STOKER Portland, Oreg.

Application April 11 1936, Serial No. 73,882

5 Claims.

This invention relates generally to underfeed stokers, and particularly to a stoker having a remote coal bin and having an ash removing mechanism through which the coal delivery 5 mechanism is driven.

The main object of this invention is the provision of an exceedingly simple and efficient form of stoker having a remote coal supply which is connected to a retort by means of a worm con- 10 veyor and in which the worm conveyor is driven from the retort end thereof by means of an ash discharging worm.

The second object is to eliminate the necessity of interposing a drive between a retort and a 15 coal bin or cutting through the furnace wall or fire pot base for the entrance of the driving mechanism or ash conveying worm.

I accomplish these and other objects in the manner set forth in the following specification as 2(1) illustrated in the accompanying drawing, in

which:

Fig. l is a side elevation of the device showing its relation to a hopper and furnace, both of which are broken away in vertical section.

Fig. 2 is a plan of the device with parts thereof broken away in horizontal section.

Fig. 3 is a perspective of the transmission case.

Fig. 4 is a horizontal section through the thrust bearing of the coal feeding worm.

Similar numbers of reference refer to similar parts throughout the several views.

Referring in detail to the drawing, there is shown a furnace casing l within which is disposed a fire pot base ll upon which rests a fire pot i2 which forms a part of an ordinary furnace from which the grates have been removed and there has been substituted therefore a tuyere section l3 between which and the fire pot section i2 exists the annular space M through which w ashes can fall into an ash compartment l5. The tuyere section it is mounted upon a retort IS.

The retort I6 is surroundedby a plenum chamber ii to which air is supplied through the air duct I2 from a fan It which is driven by a motor 20.. The motor 20 is provided with a pulley 2| around which passes a belt 22 which also passes around the pulley 23 of a transmission 24, which may beof any convenient type, but is preferably a ratchet gearing in which various gear ratios are obtainable.

The transmission 24 has a power take-off sprocket wheel 25, which through the chain 26 drives the sprocket wheel 21 which drives an inclined ash conveying worm 28 which is disposed 55 within an ash tube 29 which is provided near its upper end with an outlet spout 30 through which ashes are discharged into an ash can 3|. The upper side of the lower end 29'-A of the ash tube 29 is cut away to expose the ash worm 28.

Owing to the fact that the sprocket wheel 25 is in a vertical plane and the worm 28 is inclined, it is desirable to provide a universal joint (not shown) between these two elements.

Rotatably mounted on the retort i6 is a ear 32, whose teeth 33 mesh with the flights of the worm 26 in order that the gear 32 may be rotated by the ash worm 2B. Clinker breaking bars 32--A are mounted on the gear 32 and project upwardly through the annular space It.

On the lowermost end of the worm 28 is attached a universal joint 32 which is secured to the horizontal shaft 35 journaling in the housing 38. On the shaft 35 is secured a sprocket wheel 3'l' whose chain 38 drives a sprocket wheel 39 which is secured to the shaft 46 of the coal worm H which extends from the retort It to the wall 42 of the coal bin 43. It is desirable to provide an end thrust bearing til-A for the shaft 40 in order that the worm 4! may remain in tension at all times thereby limiting the tendency of the worm to buckle and objectionably engage the interior of the coal tube 41.

A. bearing 44 is provided at the wall 42 for the coal worm H. A clean-out box 45 is provided for the coal worm it at the point where it passes through the wall 46 of the coal bin 43. A coal tube 41 extends from the clean-out box 45 to the retort It and through this coal tube 41' the coal worm 4! extends.

The retort I6 is provided with a passageway 48 which communicates with the coal tube 41 at one end and extends through the retort It at the other end. The shaft W of the coal worm M is provided with a short section 49 of worm flight which is reversed from the flight of the worm I. The purpose of the section 49 is to prevent fuel and ashes from being driven into the far end of the passageway 48 and to facilitate the movement of fuel upwardly through the retort i6.

With this construction the air duct la, the ash tube 29 and the coal tube 41 all pass through the front wall 50 of the ash compartment i5, it being unnecessary to make any other openings in the furnace Ill than those already provided.

In some cases it may be found desirable to place the housing 36 with its enclosed sprocket wheels 31 and 39 on the outside of the furnace l0, although on account of the very slow movement of the parts, this will ordinarily be unnecessary since lubrication can be almost dispensed with.

I claim:

1. A coal stoker having in combination a coal tube, a coal compartment communicating with one end of said coal tube, a retort communicating with the opposite end of said coal tube, a, coal feeding worm within said tube extending its discharge end and means for preventing the movement of coal from said retort along the projecting end of the coal worm shaft, said stoker being characterized by having the coal worm driven from its discharge end by the ash removing worm.

2. A coal stoker having in combination a retort, a coal storage compartment associated with said retort, a coal tube communicating between said compartment and retort, a coal feeding worm within said tube extending into said compartment and having a shaft at the discharge end thereof projecting from said retort, an ash removal duct extending into the ash pit of the furnace and along one side of the retort, an ash worm within said ash duct having a driving connection to the projecting shaft of said coal feeding worm andmeans for driving said ash worm from the discharge end thereof, said coal and ash worms being substantially parallel in plan view. i

3. An underfeed stoker having in combination a coal supply compartment, a retortspaced from said supply compartment, a coal feeding tube communicating between said retort and compartment, a coal feeding worm within said tube extending into said compartment and having'a shaft end which projects from said retort,

an inclined ash removing duct having its lower end projecting into the ash space around the retort, an ash removing worm within said ash duct having means for driving same from its upper end and having a driving connection from its lower end to the discharge" end of said coal feeding worm and means for supplying air to the combustion chamber comprising a fan having an air duct communicating with the combustion -chamber, said air duct, coal feeding tube, and

ash removing tube extending through the ash pit opening of a furnace.

4. A stoker having in combination a coal supply compartment, a coal feeding tube having one end communicating with said compartment. a retort communicating with the other end of said coal feeding tube, a coal feeding worm in said coal tube extending into said compartment and extending through'said retort, said retort having an annular space formed around same through which ashes can fall, a revolvable gear mounted under said annular space provided with an upstanding clinker breaking bar which projects through said space, an ash removing worm. the flights of whose intake end mesh with said gear, means for drivably connecting the intake end of said ash removing worm with the discharge end of said coal feeding worm and means for driving said ash removing worm from its discharge end.

5. A stoker of the class described having in combination a coal storage compartment. a' retort spaced from said storage compartment, a coal tube communicating between, said retort and compartment, a coal conveying worm within said tube having its intake end projecting into said coal containing compartment and having .its discharge end projecting through said retort,

an ash conveying worm disposed alongside of said coal conveying worm, means for rotating said ash conveying worm from its discharge end and means for drivably connecting the intake and of said ash worm to the discharge end of the coal conveying worm.

EDWARD B. BIRKENBEUEL. 

